Archery bows of the compound type have become popular since 1969 when the Allen U.S. Pat. No. 3,486,495, issued in the United States. These bows are designed with eccentric pulleys at the end of the bow limbs so that the pull exerted by the archer decreases about half way through the draw. This enables the archer to maintain the draw without the excessive arm tension usually needed and thus makes it easier to aim the arrow prior to release.
The use of the pulleys on the bow limbs has resulted in anchor points and plural pulleys along an axis. Due to the nature of the cables and anchor points, there may be at least three pressure lines on a bow limb. If the tension at these three lines is not equal, there may be a tendency to twist the bow limbs especially during the periods of highest tension when the arrow is drawn.
One design to centralize the maximum tension is disclosed in a U.S. Pat. No. 4,079,723, dated Mar. 21, 1978. The present invention is an improved pulley construction which equalizes or balances the cable and pulley loads under all conditions of the bow operation. In a released position, the three-cable loads are substantially equally distributed along the pulley axis at the end of the limbs. In the full draw state, the main bowstring carrying the highest tension is moved to the center of the pulley axis and thus is central to the bow limb. There is, therefore, no twisting reaction on the bow limb itself and the release is smooth and without a torque reaction.
It is, therefore, an object of the present invention to provide a bow construction for compound, eccentric pulley bows which transfers the main bowstring tension to the center of the bow limb at drawn conditions to avoid twisting torque on the bow limbs.
It is a further object to provide a compound bow with pulleys which can be used at each end of the bow without alteration and which can be used with optional eccentricity dimensions.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with the manner and process of using the invention directed to persons skilled in the art, all in connection with the best mode presently contemplated for the invention.